SOME (VERY) IMPORTANT QUESTION FOR SCIENCE PART 1. - Class 10 PDF Download

Q1) State the cause of dispersion of white light by a glass prism. How did Newton, using two identical glass prisms, show that white light is made of seven colours? Draw a ray diagram to show the path of a narrow beam of white light, through a combination of two identical prisms arranged together in an inverted position with respect to each other, when it is allowed to fall obliquely on one of the faces of the first prism of the combination.

Answer :

White light is a combination of 7 colours. Different colours light has different speed and different wavelength. Hence for each wavelength or colours of the light refractive index is different. So they bend at different angles when passes through a prism. Thus white light gets splits into its 7 constituent colours. This process is called dispersion.
Newton allowed passing a thin beam of white light on a prism which gets split into its constituent 7 colours. Then he allowed passing these 7 colours of light through an inverted prism as shown in below figure. Only a beam of white light comes out from the second prism thus he concluded that white light is made up of 7 colours.





Q.2) Write the structure and functions of placenta in a human female.

Answer :

Placenta connects baby with mother’s body. It is a disc-like structure embedded in the uterine wall. It is a special tissue formed by the interlocking of two sets of villi, one set given by wall of the uterus and another set from the embryo. It is the site of exchange of materials between the blood of mother and baby. It provides nutrients, oxygen from mother to foetus and removes excretory substances, carbon dioxide from the foetus.